ATM Web Ed's Blog

To The Times, radius = diameter

2009-05-27T16:04:00.001+01:00

Oh dear. Further (weak) coverage of the bicycle with Reuleaux polygon wheels.

The Times begins well by explaining the principles previously touched
on here but then goes on to expose it's correspondent's belief that
the radius is the same as the diameter. That is to say, since the
diameter of a Reuleaux polygon is constant then so must be the radius
but of course this not the case. The axle of a Reuleaux polygonal
wheel will rise and fall with it's forward progress.

Furthermore, if, as in this case, the front wheel is a Reuleaux
pentagon and the rear a Reuleuax triangle, the bobbing up and down
effect will be inconstant. Very uncomfortable if not nauseating.

http://technology.timesonline.co.uk/tol/news/tech_and_web/article6366308.ece

It's a Rouleaux Triangle/Pentagon etc

2009-05-22T22:01:00.001+01:00

It has been pointed out to me that the answer to the question in my
last post is that we are talking about Reuleaux polygons. These are a
curve of constant width - that is, a curve such that, if two parallel
lines are drawn tangent to the curve, the distance between them does
not depend on their orientation.

Well, that's what Wikipedia says anyway:
http://en.wikipedia.org/wiki/Reuleaux_triangle

And this is confirmed by Wolfram Mathworld with a bit more technical
stuff: http://mathworld.wolfram.com/ReuleauxTriangle.html

I had forgotten about the rotary combustion engine which makes use of
the properties of such polygons:
http://auto.howstuffworks.com/rotary-engine2.htm

Thank you to Lyndon Baker for the original pointer to these resources.

What's do you call the shape of a UK 50p piece?

2009-05-10T21:46:00.001+01:00

Can someone remind me what you call the sort of heptagon-type shape that is the UK 50p coin?

The reason I ask? I caught this news item at Ananova about Guan Baihua, 50, a retired military officer in Qingdao, who spent 18 months developing his unique bike.

"The front wheel is a five-sided pentagon while the back wheel is a triangle, reports the Bandao City Daily." says the news item and worse still, despite the obvious curved nature of the edges, Harshpaul at http://www.automotto.org/entry/man-gets-patent-for-odd-sided-wheels-bicycle/ says "A bicycle that has straight-edged wheels doesn't sound a very smart idea".

What I do know is that the curved sides are created as a section of a circle with its centre being the diametrically opposite corner. The effect being that the diameter of the shape remains the same, so to speak, thus allowing coins of this shape to roll through a coin-operated machine's internal workings just as easily as a circular coin. A cylinder (prism?) with such a cross-section will work perfectly as a roller. However, if the load is suspended on a central axle the effect can only be uncomfortable in a bike. All the more so with a five-sided front wheel and a three-sided rear wheel.

Anyway, the question was...what is the a curved-edged polygon thingy called?

Australian politician grows 2.7 metres taller

2009-05-04T10:01:00.001+01:00

An Australian politician has had her legs lengthened according to
Ananova, an online news provider, . She is now over 4 metres tall
which should provide her with a dominating political presence in the
Logan city council chamber.

Fed up with what she saw as her diminutive height of 1.52m she paid a
Russian clinic to break her legs in four places and had them stretched
by "1mm a day for nine months". As a result, then, she is now 4.2
metres tall.

"Ms Ban was taunted at school and feared her height would damage her
credibility as she entered the legal profession and later went into
local politics." I reckon it's not her credibility that is damaged but
the basic mathematics of the journalist(s) involved.

You can read the full story here:
http://www.ananova.com/news/story/sm_3303713.html

I am so seriously under-weight...

2009-04-22T21:33:00.002+01:00

According to a report in the UK Daily Mirror...

...I am so seriously under-weight that I am amazed I am still alive.

http://www.mirror.co.uk/life-style/dieting/2009/04/22/could-this-pill-really-be-the-diet-miracle-we-ve-been-waiting-for-115875-21295493/

In a report about this new diet medication the journalist tells us
that the pill is only available to those with a body mass index of 28
or more.

To check whether I qualified, I used their formula as published and my
Body Mass Index works out at 0.037.

Using the same algorithm I calculate that in order to qualify for the
pill I would either have to weigh 110g or be 49m tall.

Try the formula yourself:

BMI is a system used to determine how healthy your weight is in
relation to your height. Here's how to work out yours:

1 Measure your height in metres and multiply the figure by itself.

2 Measure your weight in kilos

3 Divide the weight by the answer to no.1

If you qualify for the diet pill with BMI of 28 or over using this
algorithm, then do let me know!

One dollar = one cent according to American phone company

2009-02-05T15:03:00.001Z

Sometimes one can only despair...

You may remember a while back when a lottery company had to withdraw a scratchcard.

To qualify for a prize, users had to scratch away a window to reveal a temperature lower than the figure displayed on each card. As the game had a winter theme, the temperature was usually below freezing.

But the concept of comparing negative numbers proved too difficult for some Camelot received dozens of complaints on the first day from players who could not understand how, for example, -5 is higher than -6.

Well now I believe this has been trumped by Verizon, an American phone company...

Listen to a frustrated customer trying to get the customer service representatives to understand that when they quote 0.002 cents per kilobyte of data this does not mean that 35 000 kilobytes cost $70.

You just have to listen to the recorded conversation.

http://www.youtube.com/watch?gl=GB&v=lCJ3Oz5JVKs

Prime numbers and multiples of six...

2008-12-13T19:14:00.001Z

There you are happily wandering through the pre-Christmas melee when, out of the blue, something of a revelation hits you right between the primes.

We, my nine year old twins and I, had spent the day chasing Christmas trees, writing cards, sorting out the lights and all those other festive bits and pieces. Lacking energy, I caved (well it didn't take much to be honest) and agreed to chips for tea. Added the compulsory greenery and we sat down to tea with the usual demand for a quiz (sometimes its our version of Twenty Questions...). Anyway Megan's chosen subject: Maths.

Mum invents the questions and to get to the point, a discussion ensued on how to identify whether or not a number is prime. Caitlin asks: "Is three billion and 1 a prime number?" I can't answer in the time available (Strictly Come Dancing is going to start soon). Then Caitlin announces that, apparently, all prime numbers are either one less than, or one more than a multiple of six. Therefore, it seems, that you can at least say that a number is not prime if that requirement is not met.

They all rushed off to watch the semi final - the maths of the SCD quarter and semi finals is another story - leaving me to discover that this multiple of six thing is true and to wonder why I had never heard that before. Maybe it's just me that it has passed by or that has passed it by...

Nine year olds...hah!

Why do car wheels have an odd number of spokes...

2008-10-05T10:28:00.001+01:00

Sitting in a car park yesterday I was elevated in a moment of meditation to notice that the wheels on every# car I could see had an odd number of spokes.

Five spokes and seven seemed the most frequent but there was one with three spokes. There were none I could see with four, six or eight. Googling revealed this article which sort of discusses the axes of symmetry of a Ferrari wheel (five spokes) but only refers to the aesthetics rather than there being any engineering rationale behind the oddness.

A Google images search seems to indicate that odd is by far the overwhelming favourite for spokes but not exclusively so. It would seem that eight is not uncommon among what seem to be high-performance cars (those that are involved in high speed racing for example). Thus maybe it is just aesthetic. It would be interesting to hear what others think.

Event calendar now up and running

2008-09-26T16:27:00.002+01:00

After a few trials and tribulations involving sending data from the calendar through Yahoo's website for processing and back to our Calendar web page the processing of event information now works. What was the problem? Well...in order to display the map of events it was necessary to extract the address information and encode that in a form for Google maps. Bizarrely, however, Google doesn't do that, but Yahoo does - through its data 'pipes' system. The data gets fed back to Google maps automatically allwing the bat indicators on the map to plot all the events that have sufficient information in them for Yahoo to pinpoint the location.

It's all very cunning and not a little mind boggling. But, hey, it works...

At the top of the page is a link to a form with which you can submit your event. It has to go past my eyes first however in order to avoid nonsense entries etc.